def __init__(self, tdbEpoch=None):
"""Create a new AppGeoData object for a specific date.
Inputs:
- tdbEpoch TDB of apparent geocentric position (Julian year)
note: TDT will always do and UTC is usually adequate
default: current date
"""
# compute star-independent apparent geocentric data
if tdbEpoch == None:
tdbDays = Tm.utcFromPySec()
else:
tdbDays = Tm.mjdFromEpJ(tdbEpoch)
self.dtPM, self.bPos, self.hDir, self.grav, self.bVelC, self.bGamma, self.pnMat \
= llv.mappa (2000.0, tdbDays)
def __init__(self, tdbEpoch=None):
"""Create a new AppGeoData object for a specific date.
Inputs:
- tdbEpoch TDB of apparent geocentric position (Julian year)
note: TDT will always do and UTC is usually adequate
default: current date
"""
# compute star-independent apparent geocentric data
if tdbEpoch == None:
tdbDays = Tm.utcFromPySec()
else:
tdbDays = Tm.mjdFromEpJ (tdbEpoch)
self.dtPM, self.bPos, self.hDir, self.grav, self.bVelC, self.bGamma, self.pnMat \
= llv.mappa (2000.0, tdbDays)
def GeocentricFromTopocentric(self, fromP, dumV):
if self.obsData is None:
raise ValueError("must specify obsData to convert to Geocentric from Topocentric")
return (
geoFromTopo(fromP, Tm.lastFromUT1(self.fromDate, self.obsData.longitude), self.obsData),
_CnvObj.ZeroV,
)
def GeocentricFromTopocentric(self, fromP, dumV):
if self.obsData is None:
raise ValueError("must specify obsData to convert to Geocentric from Topocentric")
return (
geoFromTopo(fromP, Tm.lastFromUT1(self.fromDate, self.obsData.longitude), self.obsData),
_CnvObj.ZeroV,
)
def TopocentricFromGeocentric(self, fromP, dumV):
if self.obsData == None:
raise ValueError("must specify obsData to cnvert to Topocentric from Geocentric")
return (
topoFromGeo(fromP, Tm.lastFromUT1(self.toDate, self.obsData.longitude), self.obsData),
_CnvObj.ZeroV,
)
def TopocentricFromGeocentric(self, fromP, dumV):
if self.obsData == None:
raise ValueError(
"must specify obsData to cnvert to Topocentric from Geocentric"
)
return (
topoFromGeo(fromP,
Tm.lastFromUT1(self.toDate, self.obsData.longitude),
self.obsData),
_CnvObj.ZeroV,
)
def icrsFromFixedFK4(fk4P, fk4Date):
"""
Converts mean catalog fk4 coordinates to ICRS for a fixed star.
Uses the approximation that ICRS = FK5 J2000.
Inputs:
- fk4Date TDB date of fk4 coordinates (Besselian epoch)
note: TDT will always do and UTC is usually adequate
- fk4P(3) mean catalog fk4 cartesian position (au)
Returns:
- icrsP(3) ICRS cartesian position (au), a numpy.array
Error Conditions:
none
Warnings:
The FK4 date is in Besselian years.
The star is assumed fixed on the celestial sphere. That is a bit
different than assuming it has zero proper motion because
FK4 system has slight ficticious proper motion.
The FK4 system refers to a specific set of precession constants;
not all Besselian-epoch data was precessed using these constants
(especially data for epochs before B1950).
References:
P.T. Wallace's routine FK45Z
"""
# compute new precession constants
# note: ETrms and PreBn both want Besselian date
eTerms = llv.etrms (fk4Date)
precMat = llv.prebn (fk4Date, 1950.0)
# subtract e-terms from position. As a minor approximation,
# we don't bother to subtract variation in e-terms from proper motion.
magP = RO.MathUtil.vecMag(fk4P)
meanFK4P = fk4P - (eTerms * magP)
# precess position to B1950, assuming zero fk4 pm
# (we'll correct for the fictious fk4 pm later)
b1950P = numpy.dot(precMat, meanFK4P)
# convert position to ICRS (actually FK5 J2000)
# but still containing fk4 fictitious pm;
# compute fictitious pm.
tempP = numpy.dot(_MatPP, b1950P)
ficV = numpy.dot(_MatVP, b1950P)
# correct ICRS position for fk4 fictitious pm
# (subtract over period fk4Date to J2000)
period = 2000.0 - Tm.epJFromMJD (llv.epb2d (fk4Date))
return tempP - ficV * period
def ICRS2000FromGeocentric(self, fromP, dumV):
agData = AppGeoData(Tm.epJFromMJD(self.fromDate))
return (icrsFromGeo(fromP, agData), _CnvObj.ZeroV)
def GeocentricFromICRS2000(self, fromP, fromV):
agData = AppGeoData(Tm.epJFromMJD(self.toDate))
return (geoFromICRS(fromP, fromV, agData), _CnvObj.ZeroV)
def ICRS2000FromGeocentric(self, fromP, dumV):
agData = AppGeoData(Tm.epJFromMJD(self.fromDate))
return (icrsFromGeo(fromP, agData), _CnvObj.ZeroV)
def GeocentricFromICRS2000(self, fromP, fromV):
agData = AppGeoData(Tm.epJFromMJD(self.toDate))
return (geoFromICRS(fromP, fromV, agData), _CnvObj.ZeroV)
